Why did downtown go dark? City, Enmax mum on fire’s possible cause

Jason Markusoff, Calgary Herald10.14.2014

Enmax work crews attend to a massive power failure Sunday morning as a fire occurred in a downtown manhole Saturday night.David Moll

A handout photo showing fire damage in the concrete room under the manhole that the wires and cables pass through. The result was a large power failure through the west end of downtown Calgary.Courtesy Enmax

Enmax work crews attend to a massive power failure Sunday morning as a fire occurred in a downtown manhole Saturday night.David Moll

A massive power failure caused for numerous residents to be evacuated from their apartments downtown Sunday morning near 8th Street S.W. as a fire occurred in a manhole Saturday night.David Moll

Calgary Police and Fire departments responded to the power outage along 8th street Sunday morning. An estimated 5,000 residents are without power in west downtown and some suites above the 13th storey level are without water pressure.David Moll

Enmax work crews attend to a massive power failure Sunday morning as a fire occurred in a downtown manhole Saturday night.David Moll

Mayor Naheed Nenshi speaks to media at the Emergency Operation Centre about the ongoing power outage in the downtown and its impact to citizens.Leah Hennel

Calgary, Alberta; Oct 12, 2014 -- Calgary Police and Fire Departments respond to the power outage along 8th street Sunday morning. Power was lost to a large portion of downtown Calgary as a fire occurred in a manhole Saturday night located at 8 Avenue and 5 Street SW which completely destroyed the electrical infrastructure inside. ({David Moll}/Calgary Herald) For {C} story by {Amanda Stephenson}David Moll

Calgary,Alberta; Oct 12, 2014 -- A closed and desolate 7th street as power was knocked out to a large portion of downtown Calgary; a fire occurred in a manhole Saturday night located at 8 Avenue and 5 Street SW which completely destroyed the electrical infrastructure inside. ({David Moll}/Calgary Herald) For {C} story by {Amanda Stephenson}David Moll

Calgary,Alberta; Oct 12, 2014 -- Generators power traffic light controls along a closed 7th street S.W. (between 7 and 8th Avenue S.W.) as power was lost to a large portion of downtown Calgary; a fire occurred in a manhole Saturday night located at 8 Avenue and 5 Street SW which completely destroyed the electrical infrastructure inside. ({David Moll}/Calgary Herald) For {C} story by {Amanda Stephenson}David Moll

While the homes of 5,000 Calgarians remain without power, Calgary Fire and Enmax leaders are keeping everyone else in the dark as to what they suspect caused the blue flames that charred an underground vault downtown.

After removing 3.5 kilometres of cable and other destroyed gear, investigators are trying to piece together what exactly happened.

Calgary Fire Chief Ken Uzeloc and utility CEO Gianna Manes wouldn’t even offer a timeline for what they called a “multi-stage” probe.

“No, not ruling anything out. Not speculating as to what may have caused this and what may not have caused this,” Manes told reporters Monday.

“So we’re just going to need to, again, continue to wait.”

In an update Tuesday, Manes offered no new details, but noted Enmax was working with the fire department in its investigation.

The disaster is a first for Enmax, but explosive manholes and underground electrical fires occur throughout the world.

Be it a bad connection, human error or cables corroded when water seeped in, experts in electrical engineering and fire analysis suggest the city and its utility may already know what went wrong.

Michael Bodnar, a Calgary-based principal with fire engineering firm Sereca, said any number of things may have gone wrong, either during work on the vault or when “a bunch of really unlikely things” combined in disaster.

“Either way, I would bet they had a very good idea of what likely happened within a matter of hours,” said Bodnar, a former fire protection engineer in the hydroelectricity sector.

“They’re going to want to make sure with the least degree of uncertainty what the likely cause is before they say anything.”

Early indications could be incorrect, said Richard van Leeuwen, an electrical engineering consultant who specializes in forensic investigations.

“Some people are wrong so often that they just wind up with egg on their face,” said the Vancouver engineer, whose experience spans more than 1,000 cases.

“Sometimes these things end up in court cases and seven years later there’s no agreement on what actually happened.”

Bad connections are a common cause of underground electrical fires, Van Leeuwen said. Unlike power surges, bad connections don’t trip up circuit breakers that are the best defence against surge-based fires.

They can take a year or more to heat up and trigger fires, and are hard to spot without regular heat detection, he said.

“Once you get a bad connection, it heats up, it ignites the insulation on the cable, and you get a fire, and the power is not disconnected,” van Leeuwen said.

“So that fire travels until finally you get a short circuit somewhere, and by this time the fire can be fairly well established.”

This much is known: 127 power cables were damaged, and there were 130 high-voltage splices in the wreckage of that underground vault, according to Manes.

Enmax didn’t have fire suppression equipment in that subterranean chamber, a spokeswoman confirmed Tuesday. Van Leeuwen said that is typical, because water can cause problems of its own down there.

Corroded power cables caused by water in manholes is the most frequent cause of manhole fires, according to a 2008 article in Fire Engineering, a U.S. magazine. A bad 2014 for manhole fires across Britain also came during an unusually wet year.

While several downtown-area power vaults were inundated during last summer’s flood, the one under 8th Street S.W. was not.

“Until we can fully determine the cause of this, we aren’t ruling anything out that might have potentially impacted this section of the system, even though there was not water in this section during the flood,” Manes said.

While she predicted power would be restored by Thursday, it could take longer if the electrical damage extends beyond that one fire-damaged manhole.

“The only way we’ll be able to tell if there was further damage beyond this section is when we begin to re-energize the system,” Manes told reporters.

Among city officials, only Mayor Naheed Nenshi would posit a possible explanation, albeit a cheeky one for a city bedevilled lately by fire, September snow and flooding.

“I have been doing my own analysis of the situation, and I have pretty much ruled out zombies and aliens. Zombie aliens, however, still remain in question.”

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